Endometrial cancers are generally divided into at least two different pathogenetic types. One occurs from the proliferative endometrium, depending on continuous estrogen stimulation, while the other is not related to the stimulation and occurs from the atrophic endometrium of older post-menopausal women. In order to assess the risk factors for endometrial carcinoma (EC), a case-control study with 136 Japanese women having EC and with 376 healthy controls for ECs in Japan, together with an immunohistochemical analyses on p53, estrogen (ER) and progesterone receptors (PR) of EC patients was undertaken. Nulliparity, increased BMI, hypertension, diabetes mellitus, later age at menopause and personal cancer history were all seen predominantly in the EC group. Frequency of irregular menses, polycystic ovary syndrome (PCOS) and obesity in the EC patients under 40-year old was significantly higher than the control group. Immunohistochemical expressions of ER (P<0.05) and PR (P<0. 01) were more frequently recognized in the EC of the pre-menopausal than in the post-menopausal patients. On the other hand, p53 overexpression was detected in 27.2% of the post-menopausal EC group, while only found in 7.1% of the pre-menopausal EC group. These findings indicate that possible factors related to endometrial carcinogenesis are different between the pre- and post-menopausal EC patients. Namely, untreated ovarian dysfunction such as PCOS with unopposed estrogenic action in the endometrium may be associated with development and growth of EC in younger women, yet abnormality of p53 gene may be more concerned with the development of the post-menopausal EC, independently of sex steroid influence.